210
8331B–AVR–03/12
Atmel AVR XMEGA AU
cations. A block diagram of the pattern generator is shown in ”Pattern generator block diagram.”
on page 210. For each port pin where the corresponding OOE bit is set, the multiplexer will out-
put the waveform from CCA.
Figure 16-5. Pattern generator block diagram.
As with the other timer/counter double buffered registers, the register update is synchronized to
the UPDATE condition set by the waveform generation mode. If the synchronization provided is
not required by the application, the application code can simply access the DTIOE and PORTx
registers directly.
The pin directions must be set for any output from the pattern generator to be visible on the port.
16.6 Fault Protection
The fault protection feature enables fast and deterministic action when a fault is detected. The
fault protection is event controlled. Thus, any event from the event system can be used to trigger
a fault action, such as over-current indication from analog comparator or ADC measurements.
When fault protection is enabled, an incoming event from any of the selected event channels
can trigger the event action. Each event channel can be separately enabled as a fault protection
input, and the specified event channels will be ORed together, allowing multiple event sources to
be used for fault protection at the same time.
16.6.1 Fault Actions
When a fault is detected, the direction clear action will clear the direction (DIR) register in the
associated port, setting all port pins as tri-stated inputs.
The fault detection flag is set, the timer/counter’s error interrupt flag is set, and the optional inter-
rupt is generated.
There is maximum of two peripheral clock cycles from when an event occurs in a peripheral until
the fault protection triggers the event action. Fault protection is fully independent of the CPU and
DMA, but requires the peripheral clock to run.
Timer/Counter 0 (TCx0)
BV BVDTLSBUF
OUTOVEN
DTHSBUF
OUTx
CCA WG outputUPDATE
ENEN
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